Originally Posted by
ghostm42
Thanks for the responses. Very Interesting. So derailleur rub won't necessarily be solved with a triple derailleur. It's ones of those "you have to live with it" things. Hmm...
I hadn't considered changing the bottom bracket. The "chainline" measurement (center of tube to middle chain ring) is about 50mm, but I can still shift to the largest gear. Is a smaller chainline measurement meant to improve efficiency and reduce wear by having a relatively straight chain?
Typically, the spindle for a triple crankset is longer than a double. Putting a triple crank on a double spindle results in the small chainring pushed into the chainstay if all else is equal. If it works now, don't argue with it.